Intracranial inflammatory pseudotumor mimicking malignant neoplasm.

Disclosure. The authors declare no conflicting interests, support or funding from any drug company. Figure 1-Contrast-enhanced MRI showed a lesion (arrow) hypointense to gray matter on T1-weighted images and hyperintense on T2-weighted images with homogenous and avid contrast enhancement partially encasing the cerebral dura mater in the polus temporalis. I nflammatory pseudotumor is a non-neoplastic process with unknown etiology, and it most frequently involves the lungs and orbits. It is also characterized by proliferation of the connective tissues with inflammatory infiltrates. 1 Primary intracranial inflammatory pseudotumor is exceptionally uncommon and typically arises from the meninges with a predilection for skull base and cavernous sinus. In this report, we describe a rare lesion in the brain parenchyma of the left temporal lobe in a 41-year-old man, which was initially suspected to be a glioma and considered to be a non-Hodgkin's lymphoma after intraoperative frozen-section examination. We also describe its rare progression developing along the meninges after surgery. A 41-year-man presented with headache for 7 years and aggravation for one month. Fundus examination revealed optic disc pallor in the left eye, which also had a visual acuity of 6/24 on Snellen's chart. The vision of the contralateral eye appeared normal. The CT results showed a low-density lesion in the left temporal lobe. The contrast-enhanced MRI results showed a lesion hypointense to gray matter on T1-weighted images and hyperintense on T2-weighted images with homogenous and avid contrast enhancement partially encasing the cerebral dura mater in the polus temporalis (Figure 1). A diagnosis of glioma was considered, and he was planned for right orbitozygomatic craniotomy and tumor excision. The temporal lesion was found grayish white and mucinous intraoperatively, and increased thickness of the cerebral dura mater in the polus temporalis was also observed. Frozen-section examination showed the signs of non-Hodgkin's lymphoma. Therefore, total excision of the temporal lesion and decompressive craniectomy was performed. The final diagnosis of inflammatory pseudotumor was confirmed through histopathology. His headaches were diminished after the surgical recovery, but recurred with complaints of vision diminution of the left eye 2 months later. The MRI results showed a total resolution of the temporal lesion. There was extensive meningeal thickening, enhancement of the bilateral cavernous sinuses, high posterior clinoid area, and distal petrous internal carotid artery canals. A lesion developing along the cerebral dura mater was also observed. The patient was treated with dexamethasone at a dosage of 20 mg daily for 7 …